try spraying a line of prove a mite inthe cage ( with out the rat in there) it the same chemical they use in flea sprays. I place the rats in another container empty the tank and then spray down then set up like normal once it dry. as far as I know not issue with snakes and fleas. I spray the room once every other month to kill any possible fleas and anythign else crawling around in th room that not snake /rodent.